Acclimation strategy and nitrate supplementation significantly enhanced the ammonium tolerance of Arthrospira platensis HN5

The highly toxic effects of ammonium on Arthrospira hinder its utilization as a nitrogen source in Arthrospira cultivation and severely limit its application in treating high-ammonium wastewater. This study revealed that both short-term (12 d) and long-term (270 d) ammonium acclimation significantly improved the ammonium tolerance of Arthrospira platensis HN5, with biomass productivities of 0.14 and 0.11 g L –1 d –1 , respectively, and net photosynthetic oxygen evolution rates exceeding 60 and 50 μmol O 2 ·mg –1 ·Chla·h –1 under a lethal ammonium concentration of 15 mM. Furthermore, the ammonium tolerance of the long-term acclimated strain exhibited heritable characteristics. Additionally, nitrate (NaNO 3 ) concentrations of ≥ 0.1 mM were demonstrated to effectively enhance the ammonium tolerance of A. platensis HN5 in a concentration-independent manner. This study highlighted the role of acclimation and nitrate supplementation in improving the ammonium tolerance of A. platensis HN5, offering efficient and reliable strategies for ammonium utilization in the Arthrospira industry and for treating high-ammonium wastewater using Arthrospira . • Established effective methods to improve the ammonium tolerance of Arthrospira . • Acclimation effectively improved the ammonium tolerance of Arthrospira . • The long-term acclimated strain exhibited heritable enhanced ammonium tolerance. • The ammonium tolerance of Arthrospira was enhanced by nitrate supplementation.